Launch from Cape Canaveral (KSC); landing at Cape Canaveral (KSC); ISS 13A.1 SH-LSM ITS-S5. The launch had been delayed 24 hours the week before to get back on schedule after unexpected work to replace a suspect valve in the shuttle's crew cabin pressurization system.

The STS-118 mission delivered and assembled the starboard S5 truss segment of the International Space Station, as well as External Stowage Platform 3, (ESP-3) and a replacement Control Moment Gyroscope (CMG). The mission was also the final flight to include the Spacehab Logistics Single Module.

Following a two days solo flight the Endeavour docked to the ISS on August 10, 2007. For the next nine days the crew performed common work with the ISS expedition 15.

The Spacehab Logistics Single Module, a pressurized aluminum habitat that is carried inside the payload bay, has a capacity of 6,000 pounds (2,700 kg), and carried a variety of cargo and research projects, including supply materials for the ISS. It returned cargo, including the MISSE PEC 3 & 4, a Department of Defense payload that had been installed on the ISS. Launched in July 2006, the MISSE PEC-3 & 4 contained over 850 materials specimens that will be studied to determine the effects of long-term exposure to the environment of space.

The first EVA by Richard Mastracchio and Dafydd Williams occured on August 11, 2007 (6h 17m) to remove locks from the S5 that secure it during launch and lock it in place, relocate a radiator from its launch position to the bottom of the S5 to provide clearance for solar arrays to track the sun. During mission STS-120, the radiator will be relocated to its final position. While the EVA was underway, the primary command-and-control computer in the U.S. Destiny lab module unexpectedly shut down, but the two others worked on.

It was then decided to extend the mission for three days, because that for the first time used Station-to-Shuttle Power Transfer System (SSPTS) worked well. SSPTS transfers electrical power from the station to the shuttle, allowing the shuttle to conserve its own power generating resources. It was also reported, that foam hit Endeavour heatshield during launch. The thermal tile gouge almost reaches shuttle's skin. It was a small but deep, scooped-out pit in the heat shield. Another little damage was later found on the orbiters window.

The second EVA was again performed by Richard Mastracchio and Dafydd Williams on August 13, 2007 (6h 28m) to move a failed control moment gyroscope (CMG-3) to an unpressurized platform that holds spare parts outside the station called External Stowage Platform-2 (ESP-2), a new platform, ESP-3, was added to the station (stored inside ESP-3 is a new gyro that the spacewalkers used to replace the failed one), disconnect ESP-3 power cables to prepare it for permanent relocation to the station.

Meanwhile Mission Specialist and educator astronaut Barbara Morgan along with other crew members held the first of three planned educational event. Twenty children from Boise in Idaho had the chance to ask different questions to Barbara Morgan an her crewmates.

The third EVA by Richard Mastracchio and ISS Expedition 15 crew member Clayton Anderson occured on August 15, 2007 (5h 28m) to prepare the relocation of the P6 truss segment on the STS-120 mission, move two equipment carts from the right to left side of the station and relocate an antenna and upgrade avionics and communication systems. This EVA had to be shortened because of a damage to the left thumb of Richard Mastracchios spacesuit glove. At no time was Richard Mastracchio in any danger, NASA said, but flight rules required Richard Mastracchio to end his spacewalking task as a precaution.

Mission managers then decided, that a repair spacewalk for small gouge on Endeavour's heat shield tiles will not be needed.

The fourth and final EVA by Dafydd Williams and ISS Expedition 15 crew member Clayton Anderson was conducted on August 18, 2007 (5h 02m) to install support equipment on the S1 truss that will allow for an addition to the inspection boom during the STS-123 mission, and to install a system to provide better wireless video coverage during future missions.

Meanwhile it was also decided, to shorten the mission. The earlier landing opportunity was selected in the event hurricane Dean threatens the Houston area.